Pneumatic-hydraulic shock absorbers



May 24, 1966 B1. SCALES PNEUMATIC-HYDRAULIC SHOCK ABSOREERS 2 Sheets-Sheet 1 Filed April 22, 1965 N 'TOR. gv gmfk May 24, 1966 B. T. SCALES ,2

PNEUMATIC-HYDRAULIC SHOCK ABSORBERS Filed April 22, 1965 2 Sheets-Sheet 2 4 IN'V NT 31 y gw 3 W 7% 3,252,587 PNEUMATIC-HYDRAULIC SHOCK ABSORBERS Brian T. Scales, RD. 4, Black River Road, Bethlehem, Pa.

Filed Apr. 22, 1965, Ser. No. 450,064 Claims. (Cl. 213-43) This invention relates to pneumatic-hydraulic shock absorber devices and in particular relates to an improved shock absorber device which is especially suitable for operation in a horizontal plane.

The invention contemplates improvements in pneumatic-hydraulic devices of the kind wherein the force to be counteracted causes the device to contract and thereby force fluid to flow as between a storage chamber and a receiver chamber via a restrictive orifice which creates a cushioning effect, with recoil of the device being effected by compressed air causing the fluid to return to the storage chamber and thereby expanding the device.

Such devices can operate satisfactorily and efficiently only if the air is confined Wholly within its operating chamber. This problem is especially acute if the shock absorber is to be operated in a horizontal position;

The principal object of the invention is to provide a device of the kind in question having means which will permit the flow of fluid as between the storage and receiver chambers for a cushioning effect while maintain ing a segregated air supply for the recoil effect and to accomplish this with a minimum of mechanical parts to thereby reduce overall costs.

The invention finds a special utility in horizontally mounted railway car draft gear to provide for a cushioning effect in both bud and draw operations for absorbing the energy transmitted between adjacent cars and thereby safeguarding equipment and personnel.

The preferred form of the invention will be apparent from the description below taken in connection with the following drawings, wherein:

FIGURE 1 is a sectional plan view of a conventional railway car coupling mechanism incorporating the present invention;

FIGURE 2 is a sectional view of a preferred embodiment of the invention, the device being in an open or extended position;

FIGURE 3 is a view of the device of FIGURE 1 where the device is in a semi-contracted position; and

FIGURE 4 is a view of the device of FIGURE 1 where the device is in a fully contracted or closed position- In FIGURE 1 a device 1 constructed in accordance with the invention is mounted for operation in conjunction with a conventional railway car coupler C. The device 1 includes a cylinder member 2 and a piston mem her 3, the respective ends of which abut the stop means 4 and 5 rigidly connected with the frame 6 of the car. The mounting of the device 1 as shown provides for the piston-cylinder members to be movable relative to each other along the cylinder axis from an extended'pos'ition as shown in FIGURE 1 to a contracted position (see FIGURE 4) wherein the piston is deep within the cylinder.

When the piston and cylinder move into the contracted position the motion is resisted by a hydraulic fluid system which absorbs a greater part of the energy or force causing the piston and cylinder to move.

When forces are no longer exerted so as to cause contraction of the piston and cylinder, the action of compressed gas or air within the device causes the piston and cylinder to recoil or tend to move toward the extended position. a

As used in railway car operation, the piston-cylinder device 1 is contracted both in buff and draw operations.

When the coupler head 10 receives an impact, for

, United States Patent 0 example, a buff impact, the striker portion 11 engages the piston 3 and tends to move the piston Within the cylinder 2, the cylinder being supported against the stop 5. When the coupler head 10 receives a draw or tension force, the key 12 in the striker picks up the yoke 13 so that the loop 14 of the yoke engages the cylinder. This causes the cylinder to slide over the piston, the piston being immovable by virtue of being fixed against the stop means 4.

The details of construction of the device 1 will be explained below in connection with FIGURE 2.

The cylinder 2 includes a head 15 and a tubular body 16 having an inside surface 17. The tubular member 16 and the head 15 in part form the cylinder chamber 20. Secured to the head 15 is a metering pin 21 which is coaxial with the cylinder axis.

The piston member 3 comprises the tubular member 22 to which is fixedly secured the head 23. An end cap means 24 is mounted on the other end of the tubular member 22. The end cap 24, the head 23 and the tubular member 22 form the piston chamber 25.

The end cap 24 is provided with an orifice 26 which is adapted to cooperate with the metering pin 21 to control the flow of fluid through the orifice. As will be understood by those skilled in the art, the orifice 26 and metering pin 21 are precision machined although not necessarily precision finished.

The nylon bearings 27 engage the inner surface 17 of the cylinder and mount the piston and cylinder together for reciprocal motion along the cylinder axis. The mounting of the heads 15 and 23 in the frame 6 prevents relative rotation of the piston and cylinder members. The piston is provided with a seal 28, piston ring 29 and wiper ring 30, all of which react against the surface 17.

The inside surface 17 of the cylinder is precision machined and finished soas to provide a proper guide for the nylon bearings 27, but most important to provide a proper surface for operation of the seal 28 and piston ring 29.

Mounted on the end cap 24 is a deflector tube 31 which comprises a portion 32 connected to the end cap and surrounding the orifice 26. A second portion 33 is connected to the portion 32 and extends downwardly transverse the cylinder axis toward the bottom of the piston chamber 25. The open end 34 of the deflector tube is contoured to accommodate the contour of the tubular member 22.

In FIGURE 2 the piston and cylinder are in the fully extended or open position. As indicated, the stop members 4 and 5 determine the open or extended position of the piston and cylinder members. Under this condition the chamber 20, the deflector tube 31 and the bottom portion of the piston chamber 25 are filled with a fiuid such as oil. The space in the piston chamber 25 above the oil level 35 is filled with compressedair or gas. The seal 28 and piston ring 29 seal off the chamber 20.

Oil and air are admitted to the piston and cylinder chambers via the fitting 36. In filling, a predetermined amount of oil is injected and then compressed air is released into the cylinder. The air reacts against the oil level 35 and forces the same up through the deflector tube into the chamber 20. The amount of air introduced must be sufiicient to create a pressure to cause the oil to fill the chambers and deflector tube as indicated. This causes the piston to be firm against the stop member 4 and the cylinder firm against the stop member 5 or in the fully extended position.

When the device is in the extended position and is subjected to a buff load, the striker 11 moves the piston to the right as indicated in FIGURE 3 so that the piston and cylinder members assume a semi-contracted position. This motion causes the oil in the chamber 20 to flow out through the orifice 26, through the deflector tube 31 and into the piston chamber 25. The oil level in the chamber 25 is raised which has the effect of further compressing the air.

When the device is in the extended position and is subjected to a tension load, the loop 14 of the yoke moves the cylinder to the left as indicated in FIGURE 4. For descriptive purposes the tension load is assumed to have moved the cylinder so that the device is in the fully contracted position. In this position the end cap 24 and head 15 are slightly separated. The fully closed position is determined by stop means preferably in the form of the left hand end of the tubular member 16 engaging with the head 23.

When the piston and cylinder have been moved to the fully closed position, then virtually all of the oil in the chamber 20 has moved through the orifice, through the deflector-tube and into the piston chamber and operates to further compress the air.

The motion of the oil through the orifice is controlled by the metering pin 21. This functions in a known manner to throttle the oil and hence build up a force to resist the force which is causing the relative motion of the piston and cylinder. Thus, the moving force is, for the most part, dissipated by the oil throttling action.

When the forces causing the piston and cylinder to move as indicated in connection with FIGURES 3 and 4 are removed, the pressure of the compressed air in the cylinder 25 causes the oil to move back through the de flector tube, through the orifice 26 into the chamber 20. The effect of this, of course, is to move the piston and cylinder in a direction towards the fully open or extended position. The force causing this motion is relatively small so that the relative motion of the piston and cylinder is proportionately small, hence, the velocity of the fluid through the orifice is at a relatively low rate. Thus, excessive forces to retard the recoil are not built up in the orifice.

The open end 34 of the deflector tube is positioned and the stop means 4 and 5 and the volume of liquid are selected so that the open end 34 always remains below the liquidlevel 35 whether the piston and cylinder members are in the extended or contracted position or any position intermediate thereto.

It will be apparent that the deflector tube serves the function of isolating the compressed air solely within the cylinder chamber 25 and this isolation is maintained irrespective of the relative position of the piston and cylinder. This has two important advantages as noted below.

The air in the piston chamber 25 is always in condition to serve its primary function of operating on the oil to force the piston and cylinder members back into an extended position from which they are ready to cause development of counteracting forces. This is important because the piston and cylinder are always in a condition for development of counteracting forces immediately upon engagement'by the striker 11 or loop 14. This eliminates lost motion and time delay. Thus, the energy absorbing function of the device is enhanced;

For maximum shock absorbing capabilities, it is important that throttling effect of the orifice be immediate and predictable. Air in the cylinder 20 would necessarily delay and minimize the throttling action of the fluid in the orifice. The absence of air in the chamber 20 eliminates undesirable characteristics and contributes to the efliciency of the device.

The device described obtains a cushioning effect with a segregated air supply and does so with a minimum of overall cost. As will be apparent to those skilled in the art, the various components can be constructed with conventional materials and using conventional techniques. Machining, which is among the most costly manufacturing operations, is held to an absolute minimum with the structure described. The only part which requires a highly accurate and precision machining and finishing is the inside surface 17 of the cylinder 3. In the main, this is to insure proper operation of the seals. All other components can be finished Within the usual commercial tolerances. 7

Before closing, it is pointed out that the cylinder cham ber 20 is in the nature of an oil storage chamber in that it stores the oil in ready condition for flowing through the orifice and developing the cushioning effect. The piston chamber 25 is anoil receiver chamber in that it takes up the oil from the cylinder chamber 20 after it has passed through the orifice;

I claim:

1. A shock absorber comprising:

a hollow cylinder member formed with a chamber for carrying fluid;

a hollow piston member formed with a chamber for carrying fluid and mounted in said cylinder chamber;

means mounting said members to be movable relative to each other in a direction along the cylinder axis from an extended position to a contracted position and the mounting means orienting said axis generally horizontal;

stop means deter-mining said extended and said contracted positions;

an end cap on said piston defining one end of said piston chamber;

means forming an orifice in said end cap;

a deflector tube having a first portion connected to said end cap and surrounding said orifice and extending along said axis into said piston chamber and a second portion connected to the first portion and extending downwardly of said axis and terminating in an open end disposed adjacent the bottom of the piston chamber; and

a metering pin on one end of said cylinder and extending into said orifice and said first deflector tube portion when the piston and cylinder members are in said contracted position.

2. A construction in accordance with claim 1 further including liquid filling the space in said cylinder chamber and in said deflector tube; liquid partially filling the space in said piston chamber and covering the end of said deflector tube; compressed gas filling the space above the liquid level in the piston chamber and exerting pressure on the liquid surface;

said deflector tube and said orifice providing communication for the liquid to flow between said chambers upon relative movement of the piston and cylinder members, said pressure urging the liquid to flow in a direction from said cylinder chamber through the deflector tube and orifice into said piston chamber, and the volume of said liquid and said stop means cooperating to provide that the open end of the deflector tube is below the liquid level in both said extended and contracted positions. 3. A shock absorber comprising: a hollow cylinder member formed with a chamber for carrying fluid; a hollow piston member formed with a chamber for carrying fluid and mounted in said cylinder chamber; means mounting said members to be movable relative to each other in a direction along the cylinder axis from an extended position to a contracted position and the mounting means orienting said axis generally horizontal; i stop means determining said extended and said contracted positions; an end cap on said piston defining one end of said piston chamber; means forming .an orifice in said end cap;

a deflector tube having a first portion connected to said end cap and surrounding said orifice and extending along said axis into said piston chamber and a second portion connected to the first portion and extending downwardly of said axis and terminating in an open end disposed adjacent the bottom of the piston chamber; and

means in said orifice to control the flow of fluid through the orifice.

4. A shock absorber comprising:

a hollow cylinder member formed with a chamber for carrying fluid;

a hollow piston member formed with a chamber for carrying fluid and mounted in said cylinder chamber;

means mounting said members to be movable relative to each other in a direction along the cylinder axis from an extended position to a contracted position and the mounting means orienting said axis generally horizontal;

an end cap on said piston defining one end of said piston chamber;

means forming an orifice in said end cap;

a deflector tube connected to said end cap and surrounding said orifice and extending downwardly of said axis and terminating in an open end disposed adjacent the bottom of the piston chamber; and

means in said orifice to control the flow of fluid through the orifice.

5. A shock absorber comprising:

a hollow cylinder member formed with a chamber for carrying fluid;

a hollow piston member formed with a chamber for carrying fluid and mounted in said cylinder chamber;

means mounting said members to be movable relative to each other in a direction along the cylinder axis from an extended position to a contracted position and the mounting means orienting said axis generally horizontal;

an end cap on said piston defining one end of said piston chamber;

means forming an orifice in said end cap; and

a deflector tube connected to said end cap and surrounding said orifice and extending downwardly of said axis and terminating in an open end disposed adjacent the bottom of the piston chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,955,349 4/1934 Stevens 2l343 3,009,584 11/1961 Gibson 2l3- 4' 25 ARTHUR L. LA POINT, Primary Examiner.

BURTON FAUST, Assistant Examiner. 

1. A SHOCK ADSORBER COMPRISING: A HOLLOW CYLINDER MEMBER FORMED WITH A CHAMBER FOR CARRYING FLUID; A HOLLOW PISTON MEMBER FORMED WITH A CHAMBER FOR CARRYING FLUID AND MOUNTED IN SAID CYLINDER CHAMBER; MEANS MOUNTING SAID MEMBERS TO BE MOVABLE RELATIVE TO EACH OTHER IN A DIRECTION ALONG THE CYLINDER AXIS FROM AN EXTENDED POSITION TO A CONTRACTED POSITION AND THE MOUNTING MEANS ORIENTING SAID AXIS GENERALLY HORIZONTAL; STOP MEANS DETERMINING SAID EXTENDED AND SAID CONTRACTED POSITIONS; AN END CAP ON SAID PISTON DEFINING ONE END OF SAID PISTON CHAMBER; MEANS FORMING AN ORIFICE IN SAID END CAP; A DEFLECTOR TUBE HAVING A FIRST PORTION CONNECTED TO SAID END CAP AND SURROUNDING SAID ORIFICE AND EXTENDING ALONG SAID AXIS INTO SAID PISTON CHAMBER AND A SECOND PORTION CONNECTED TO THE FIRST PORTION AND EXTENDING DOWNWARDLY OF SAID AXIS AND TERMINATING IN AN OPEN END DISPOSED ADJACENT THE BOTTOM OF THE PISTON CHAMBER; AND A METERING PIN ON ONE END OF SAID CYLINDER AND EXTENDING INTO SAID ORIFICE AND SAID FIRST DEFLECTOR TUBE PORTION WHEN THE PISTON AND CYLINDER MEMBERS ARE IN SAID CONTRACTED POSITION. 